Recently my client told me all of a sudden his website started loading slowly. When I checked out with pingdom tools, I realized it is taking exactly 60 seconds to load. Changed the template to another one, still the same thing, and disabled all modules, cleared cache, and still the same thing. THe only thing I hven't done yet was to disable all plugins, because he's got too many plugins, anyway, I believe it is not the plugins, as the page load is happening only in the homepage.
I'm working on it right now.
EDIT: My bad, the problem also happens in the other pages.